1. Field of the Invention
The present invention relates to prosthetics and, more particularly, to an anchoring system for post-operative prosthetic devices for above-the-knee amputation patients.
2. Description of the Background
There are a variety of different types of prosthetic devices for patients that have had either transfemoral (above-knee) or transtibial (below the knee) amputation. Typically, post-operative prosthetic devices for either type of amputation patients begin with a liner, which is rolled on to the residual limb. The liner is a soft, stretchy material that acts as an interface with the prosthetic.
Once the liner is on, the residual limb then slides into a hard socket. This socket is specially made to fit and can be made out of a variety of materials.
The hard socket for a transfemoral prosthesis has a knee joint connected to it, and the more fluid and natural the movement of the knee the better. Transtibial prosthetics have no knee joint. In both cases (with or without a knee joint) there typically is an aluminum or carbon fiber tube to which a foot module is connected.
For example, U.S. Pat. No. 5,653,766 to Naser issued Aug. 5, 1997 shows a prosthetic device 20 having a generally cylindrical socket 24 with an opening for receiving an amputated limb. The socket 24 is closed at the other end, and is mounted on a bendable knee joint. Once the limb is properly received within the socket 24, straps 38 are adjusted so that a secure fit is achieved. The patient then is able to walk using the prosthetic device 20.
With all such transfemoral and/or transtibial prosthetics (above & below the knee), it is very important that the socket be securely fitted to the limb and secured in place. Stability is a common problem as many existing anchoring systems use a single attachment point to hold the residual limb in place, and this typically leads to extraneous pivoting, rotation and shift during ambulation. Moreover, it is important to be able to adjust the anchoring system periodically because the mass of the limb may change significantly over the course of a day. The above-referenced '766 patent uses a radial pressure-fit imposed by tightening two belts. However, this tends to squeeze the limb unevenly and adds to discomfort. Moreover, the radial pressure tends to pop the limb out of the socket over the course of a day.
Another well-known ICEX® Socket System uses a combination lanyard and pin kit as a docking and locking mechanism. The socket has a distal pin that docks with the prosthesis. A lanyard is connected to the liner through a slot in the bottom of the socket. The lanyard is pulled to allow the patient's residual limb, which is enclosed in the silicone liner, to be drawn into the socket by the lanyard. The lanyard is then anchored to the front of the socket. The lanyard has the advantage of allowing for adjustment of position within the ICEX Socket. If the limb changes position because of volume change and the distal migration of the limb into the socket, the prosthesis can easily be adjusted by the lanyard to compensate. The lanyard method of donning the socket also significantly reduces pain directly related to the donning process with a pin-locking mechanism. However, it has been found that many amputees lack the room for, are unable to tolerate, or have difficulty engaging the distal pin. Others complain of pain associated with engagement of the pin.
There are a number of “suspension” type sockets that eliminate the pin. U.S. Pat. No. 6,645,253 to Caspers issued Nov. 11, 2003 shows a suction system that employs a vacuum pump to impart suction to the liner, the vacuum pump doubling as a shock absorber for the artificial limb. Commercially, this is known as the Harmony® System which pulls air from the sealed socket and evacuates moisture (sweat) buildup. A nonporous polyurethane liner (not shown) is fitted over the residual limb and is inserted in the socket. A vacuum pump is attached via a connector block beneath the socket to create a vacuum force which is coupled by a tube to the liner, thereby evacuating air and sealing it to the residual limb. This provides a total-contact hypobaric suction equal weight distribution socket liner which tacks up to the skin of the residual limb and provides total contact with the limb.
U.S. Pat. No. 6,793,682 to Mantelmacher discloses a “Sure-fit Prosthetic Attachment System” (known commercially as the KISS® System) for a transfemoral and/or transtibial prosthesis, comprising a liner for enveloping an amputee limb. The liner has a buckle suspended toward the upper end, and a corresponding strap fixedly attached on the bottom end of the liner. The anchoring system also includes a containment socket for seating the liner. The containment socket has a pair of slots there through at positions corresponding to the buckle and strap of the liner, respectively. To apply the anchoring system, the patient first applies the liner to his/her limb. The liner is then inserted into the socket with the fastening strap and buckle protruding out through the respective slots. The fastening strap is then threaded up through the buckle (running upward along the side of the socket) and are inserted there through. The patient pulls down on the strap and it works by pulley action to draw the liner down into the socket until the liner is securely seated in the socket. When fully seated, the fastening strap is secured to itself by Velcro. The foregoing forms a suspension which holds the prosthesis on. Moreover, the fastening straps through slots absolutely prevent lateral shift as well as rotation. On the other hand, the patient need only readjust the Velcro closure to adjust the position of the limb within the socket. Thus, if the limb changes position because of volume change and the distal migration of the limb into the socket, the prosthesis can easily be adjusted to compensate.
It would be greatly advantageous to modify the above-described KISS® attachment system to provide a dual-lanyard fastening system alongside the socket so that the patient pulls down on one strap to draw the liner down into the socket until the liner is securely seated in the socket, and then the two opposing straps of the dual-lanyard type anchor are attached by Velcro™ to prevent extraneous up and down motion, pivoting, rotation and shift during ambulation.